The organisation was formed in Tauranga in 1990 and to date has provided ship-based medical services for about 400,000 people.
M/V Pacific Hope was bought in Japan and brought to New Zealand with the help of $700,000 of donations from New Zealand.
On Sunday the organisation's patron, Tauranga Mayor Stuart Crosby, will mark the completion of the refit of the bow section of the ship.
"We like to mark each milestone and we are also celebrating the contribution the city has made to Marine Reach and the people instrumental in getting the ship ready," said Mr Misa.
Work should be completed in time for the ship to sail for Vanuatu, Fiji and Samoa in May.